Caging The Beast

How to mic pianos

I have a lyric, “88 ebony and ivory blisses”. Many people feel that way about the piano – until they have to record it. The piano is big, complex, has a frequency range as large as human hearing. Plus, there are hundreds of different kinds. It’s a beast, and caging it is said to be the most frustrating thing in recording, but I think of it differently. For me, it’s the instrument with the most possibility. But “possibility” means variables, and that can be overwhelming, so I’ll try to get you started here.

I won’t go into the history or construction of a piano; you can look at previous articles by Michael Schulze and Nathan Rosenberg for that. I’ll just dive into miking it, and try to cover as many bases as possible. I’ll focus mainly on grand pianos, but I’ll give lip service to uprights.

The way I think about miking the piano is to first visualize the instrument and the room it’s in. I picture all the places a mic could go, and think about what that will sound like. I might even have someone play while I put my head in those spots.

Next, I think about how the piano can be manipulated. There are four basic states: open, half stick, closed lid, and lid removed. Where the instrument is in the room, the room itself, and playing style are also factors I lump into this category. I also put “problems” in this category: noisy pedals, overly bejeweled player, clicky fingernails, rattling keys, creaky benches, tuning issues, etc.

Next is context. Is it a concert or a recording? Is it a solo or group piece? Are there other instruments playing in the room? Classical? Pop? Rock? Where on the piano will we be playing? All of these factors influence your choices in miking up the beast.

Last, I think about the mic, pickup pattern and technique. Dynamics are rarely used in piano miking because the heavy diaphragm lacks the ability to capture high end nuance, but it’s not unheard of. Both large and small diaphragm condensers and ribbons are common, usually with an omni or cardioid pattern. Techniques boil down to spaced or coincident, and there are several flavors of each.

I’ll center around placement, and consider other variables around that.

Room Micing

Many engineers would disagree with this, but I think there are no wrong places to mic a piano. It depends on what you want to hear. For example, if you want a muddy sound, you could go behind the lid, but usually the accepted place to mic any instrument is in front of where it fires. With a grand piano, that’s in front of the open lid, which is a large area. As with anything, the closer the mics are, the less room sound you get. This is a place to consider context. In classical recording, it’s typical to place mics in the room. You will notice the piano sounds even and live this way. How far back depends on the room, but try 2 or 3 feet back for a relatively close sound in a decent room, and go back from there. Try head high when you’re closer, or draw an imaginary line along the angle of the lid. Place the mics around where that would line would be – higher if farther away. This can help with capturing high frequencies reflecting from the lid.

With the lid at half-stick, high frequencies reflect more downward than into the room. So you won’t get as much high frequency brilliance with a half closed lid and room mics – a duller sound. Closing the lid and room miking really won’t work, unless you want major high frequency attenuation and a muddy sound. In the classical context, we usually leave the lid fully open.

As far as mic choice, small diaphragm condensers work great. Large diaphragm condensers are awesome too, but small diaphragms have a better off axis response, which is nicer for capturing reflections. You can do a cardioid pattern here, but if the room is nice, an omni pattern might be better. Even in omni, point the mic at the source (downward toward the strings), because there will always be SOME off-axis coloration.

Figure 1 – Spaced Pair

You can choose between a single mic, a spaced pair (Figure 1), or a coincident pair like an X-Y (Figure 2). A spaced pair is straight forward but comes with two potential problems: phase and “hole in the middle”.

Figure 2 – X-Y Pair

If they’re spaced too wide (Figure 3), you could get a feeling of having a hole in the middle of the stereo field. You can bring them a little closer, or you can try adding a third in the middle.

Figure 3 – Very Wide Spaced Pair

The other potential issue is phase. As your spaced pair is summed to mono (which still happens quite a bit in broadcasts), you could find a major change in tonality based on complex phase interactions. Careful placement and checking in mono can help, or you can change your technique to an X-Y placement. This will create a more natural stereo image, eliminate any “hole in the middle” issues, and (mosty) take care of phase and mono compatibility issues. That makes X-Y configuration seem superior, but I myself am more likely to use a spaced pair.

In front of the lid or way out in the room is not the only room miking option. You can also try a behind the player placement. An X-Y slightly above the player’s head, pointing down toward the strings (not the keys) is good, and I like to put a spaced pair 2 or so feet behind the player, 3-4 feet apart (Figure 4).

Figure 4 – Behind The Player Spaced Pair

There’s no reason not to try various locations in the room or multiple mics simultaneously. You’re under no obligation to use all the tracks in your mix. One of my recent sessions was miked with 4 spaced pairs of small diaphragm condensers. One was 2 feet apart at the edge of the piano, another was 4 feet apart about 4 feet back, another was about 10 feet back, 8 feet apart, and another was a pair behind the player. I varied my use of the tracks in the mix, but I found that the farthest room mics added nothing, because the room was fairly dead. Don’t be afraid to experiment, and throw away what doesn’t work.

Close Miking

Close miking a piano is more typical of pop and rock music, and is, to me, more complex and interesting. There are a million ways you could achieve something cool with close miking.

Any placement starting at the edge of piano and moving in toward the strings we’ll call close miking. I like a spaced or X-Y pair right at the edge of the case, where it curves, about two feet above the edge. Another set up I like is a spaced pair of 414’s a little deeper into the piano, but still a good 2 or 3 feet above the strings. As you move toward the strings, you’ll find more distinction, ie: certain strings will be emphasized more. This isn’t always good, so you want to play with placement and think about where the song is mostly played.

Another technique is to use an X-Y pair in the middle of the piano, using cardioid patterns. The directionality of the cardioid pickup in this situation can pick out the high and low strings.

Recently I put an omni 414 deep into the piano, about 6 inches above the low strings and 3 inches behind the dampers, to emphasize a line that was played only on the lowest octave. This track I centered in mono, but there were 3 other tracks to mix with: a 414 a foot above the highest strings, and a spaced pair at the edge of the case. The latter 3 were for overdubs higher on the piano, but I recorded all the tracks on all three takes.

All of these placements use an open lid, and I’ve used both cardioid and omni patterns to great effect. With a half stick lid, shoving mics inside gets trickier, but this might be preferable when other players are in the room. It’s also typical to use blankets to help isolate from the rest of the band. Half-closing the lid changes the acoustics inside the piano, but not THAT much.

Closing the piano entirely is another story. First off, you can’t stick booms inside a closed piano, and as I mentioned, room miking a closed piano doesn’t work. A traditional solution is PZM mics taped to the underside of the lid. With care, you can get cabling out of there without too much disturbance, and you can even pile on more blankets for isolation. The problem with putting PZMs inside a closed piano is a boxy sound. The inside of the piano is an insane place acoustically with the lid closed, and decent PZMs do an ok job, but it’s still tough.

There is a solution I like for that dilemma. It’s the Earthworks Audio PianoMic (reviewed in the September 2011 issue). The PianoMic mounts inside the piano (Figure 5), allowing the lid to fully close. The mics attached to the adjustable boom are what’s called “random incidence” mics, which means they “don’t care where the sound is coming from”. Basically, they’re “super duper omni directional”. This matters because sound inside the piano comes from all directions, making locating a specific source difficult.

Figure 5 – Earthworks PianoMic mounts inside the piano

Earthworks was kind enough to send me a loaner for this article, and I did some testing in an environment not ideal for recording: a showroom. Alex Boggs at 88 Keys Piano Warehouse here in Albuquerque (88KeysPianoWarehouse.com) generously lent me their space, where I installed the PianoMic on a baby Yamaha. The environment was relatively noisy due to street traffic and air conditioner noise, and I was curious how well I could isolate by closing the lid. I also tested with the lid open and at half stick. The playing masked the room and traffic noise, so isolation became less of a question. I really liked the sound; I did notice that with the lid closed, it was slightly darker and boxier, but less than I expected. What impresses me about the PianoMic is that it takes the guesswork out.

Figure 6 – PianoMic goosenecks can be re-posititioned

The mics sit on tiny goosenecks so there is some play (Figure 6), but really not that much choice in the grand scheme of things. This makes miking the piano less overwhelming. You sacrifice some flexibility, but I like the efficiency. I especially like that notion for live situations, and lo and behold, Earthworks makes a touring version of the PianoMic which breaks down more for easier transport.

Even with great mics, a closed lid is the least desirable scenario, but when you must close the lid, I like the PianoMic.

For an open lid, I already described spaced and X-Y pairs placed either at the edge of the case, or deep within the piano. I tend to gravitate toward the player, and I’ve spaced two 414’s as wide as the width of the piano, 2 inches from the strings, right up on the hammers. Another option is to bring that pair together, or X-Y a pair of small diaphragms right up near the hammers toward the middle. This will yield a percussive sound with a lot of attack. Any of these techniques might get you a lot of pedal noise, though, and depending on the player and piano, that may be too much.

You might solve that problem by going to an overlooked spot on the piano: the foot. In Nathan Rosenberg’s article on Recording’s site he says, “there is a wonderful place at the tail, just about where the back leg is, or often just outside the case. Here, the various registers tend to project in a surprisingly uniform manner.” That’s a good place for a mono recording, too. Thanks, Nathan!

Another accepted technique is to place one mic toward the middle of the group of high strings (toward the music stand) and a second more toward the foot of the piano. Typically these would be condensers in omni configuration.

Another extreme option is what Elton John producer Gus Dudgeon did – remove the lid. This allows you to hang mics above the strings almost anywhere your heart desires. It can result in a considerably brighter sound with less low end power, and that may not be for everyone, but some people swear by it. A spaced pair of omnis about 2 or 3 feet above the strings would be reasonable.

Figure 7 – Miking the sound hole

Of course there are the “sound holes”, which aren’t really sound holes, but can yield some interesting results. One technique involves an X-Y pair about halfway between the lid and case, pointed diagonally toward the strings. People have also been known to stick a directional mic right down into a hole, usually as a supplement to more traditional techniques (Figure 7). This is the one situation where a dynamic might suit you. I once put an SM57 in the middle hole, ran its cable directly to two guitar pedals (delay and distortion), ran that to a vintage Fender amp, and miked that amp like I would a guitar. I put the amp in an isolation booth across the room and closed the door and it was STILL feeding back! The point is, there are any number of creative things you can do, like miking under the piano to help bolster your low-end or for a mellow sound (Figure 8).

Figure 8 – Miking under the piano

Indeed, there’s an endless variety of spaced pair, X-Y, mono and multi-mic configurations you can try. We’ve talked mostly about condensers because that’s more common, but in any of the situations I’ve described, you could substitute ribbons. We’re not done though. We haven’t talked about the mid-side pair, which can be a great way to use ribbons.

A mid-side pair makes use of two mics to create 3 tracks. Mic 1 – the “side” – must use a figure 8 pattern. Mic 2 – the “mid” – is a cardioid, pointed at the sound source. The side mic is perpendicular to the mid, so the figure 8 is left-right of the source direction. Once recorded, the side is doubled and one side is phase-reversed. These two tracks are panned hard and the mid is placed in the center. You can then mix to taste. A mid-side pair can be quite beautiful on a piano, and is perfectly mono-compatible since the 2 sides will cancel when summed. Placement of an effective mid-side pair for piano is similar to other placements – there are plenty of great possibilities. The other day I set up a mid-side pair at the edge of the case (Figure 9), right where I would normally put a spaced pair.

Figure 9 – Mid-Side pair at the edge of the piano

I loved the result. I also loved the result when Houston engineer Rock Romano recorded me with a mid-side of ribbons placed about the middle of the piano, with the cardioid pointed right at me. However, I do find that a mid-side can go wrong a little easier than other techniques. The experimental set up in Figure 10 was placed near the edge of the case a little higher, and I found the result lacking depth and character. I ended up killing side two and panning the mid left and the original side right to salvage the take.

Figure 10 – Mid-Side pair higher near the edge of piano

That brings me to a point on mixing. It may seem there’s no room to play in mixing a piano, but that’s not true. Especially if you use multiple mics, there are many ways to experiment and adjust. For example panning an X-Y closer together is always an option. A spaced pair will start to change tonally as you bring the panning in (because of phase issues), but that tonal change may be something you like. Just as there are no wrong ways to mic a piano, there are no wrong ways to mix it.

Before I end, I’d like to give my promised lip service to uprights.

Upright pianos aren’t recorded nearly as often as grands, and the reason is simple: they don’t sound as awesome. But that doesn’t mean it never happens. Some general concepts still apply. Condensers and ribbons usually work better, spaced pairs have more phase issues than X-Y pairs, and close miking yields less room sound than getting farther away. The upright is physically different though. So where do we place mics? There are three basic possibilities: Inside or above the top (with the top open), in front of the piano underneath the keys, or behind the piano. Upright pianos are often shoved up against a wall, and it’s probably best to not do that. It’s also probably best to remove panels either in front or in a back, to give better acoustic access to the sound board and strings. My personal preference would be a spaced pair of cardioid condensers placed about 2 feet off the ground, right about even with either side of the bench, so the piano player kicks them when sitting down or getting up, with panel removed. I once shoved a cheap dynamic into a 100 year old out of tune monster and the result was…magnificent…in its way.

By now you’ve got the picture that piano miking is a complex and variable task, with a lot of room for creativity. I’ve covered as much as I could, leaving out one big possibility: surround. That’s a can of worms that I think deserves its own article. Talking about piano miking is by no means simple, and neither is getting what you want from such a complex instrument, but I hope you’ve at least got some places to start now, and at best, a better idea of what to expect when caging the beast named Piano.

In case you’re wondering, I put together a bunch of notes and samples from my session with the EarthWorks PianoMic – you can get all that stuff for free right here.